Answer this question truthfully
### Question: What causes mastoiditis?
### Response: The most common cause of mastoiditis is bacterial infection after or during middle ear infection. The causes are Streptococcus pneumoniae, Streptococcus pyogenes, and Staphylococcus aureus . Staphylococci, Pseudomonas species and polymicrobials present predominantly seen in non-acute mastoiditis.